Yes Charlie was exaggerating when he gave Peter an estimate for
the time thatwould be required using a brute force attack to crack
the encryption key.

Charlie told Peter that it would take two or three hundred
million years or so to get the plain text of the encrypted file
using the brute force method.

Each encrypted file is given a passphrase. By using the
passphrase only, the encrypted file can be opened.

In case the passphrase is forgotten by the individual, by using
the software called PKI, encryption file can be recovered. To
recover the encrypted file, there is a feature that comes along
with the PKI software called the key recovery which is used to
crack the key.